Touch panel

ABSTRACT

A touch panel is presented, which includes a first substrate, a second substrate, and a third substrate. The first substrate includes a first side having a first circuit. The second substrate includes a first side arranged on the first side of the first substrate and a second side having a second circuit. The third substrate is arranged on the second side of the second substrate. Therefore, by using the structure of the touch panel, the substrates of the touch panel can be integrated, so as to achieve the objective of decreasing the overall thickness of an electronic device.

FIELD OF THE INVENTION

The present invention relates to a touch panel, and more particularly toa capacitive touch panel.

DESCRIPTION OF THE PRIOR ART

In a conventional capacitive touch panel, in addition to liquid crystaland a color filter, at least an extra glass substrate is needed for atouch circuit. Indium tin oxide (ITO) having a strip pattern is providedon two sides of the glass substrate, and the upper and lower layers ofthe ITO are perpendicularly arranged. A metal wire is formed on a sideof the glass substrate. The formation of the ITO electrodes and themetal wire is a key factor that influences the fabrication cost andquality in the process of forming the touch panel.

FIG. 2 shows a conventional method for fabricating a touch circuit in atouch panel. In the conventional method, a circuit is formed bywet-etching. First, a glass substrate formed with ITO on two sides iscleaned. Next, a photoresist is applied onto the ITO on a first side ofthe substrate. After the processes of pre-baking, exposure, anddevelopment of the photoresist, the photoresist is applied onto theentirely of the ITO on a second side of the glass substrate opposite thefirst side, so as to protect the ITO on the second side of the glasssubstrate. Subsequently, the glass substrate is immersed in an etchant,so as to remove the undesired ITO on the first side of the substrate.Afterward, the photoresist on the two sides of the substrate is removed,and a first circuit on the first side of the glass substrate is formed.

Next, the method for patterning the ITO on the first side of the glasssubstrate is repeated to pattern the ITO on the second side of thesubstrate, so as to form a second circuit on the second side of thesubstrate.

In the conventional wet-etching process, the steps of applying thephotoresist and removing the photoresist need to be performed twice. Ifliquid crystal or a color filter is already formed on a side of thesubstrate, the steps of applying the photoresist and immersing in theetchant may cause damage to the liquid crystal or the color filter.Thus, in the conventional method for fabricating the touch panel, thetouch circuit and the liquid crystal or the color filter need to beformed on different substrates, which are then combined with thesubstrate having the touch circuit.

Due to the demands for light, thin, short, and small electronic devices,many hand-held electronic devices are required to be lighter and thinnerfor easy portability. However, the conventional wet-etching processincreases the complexity of integrating the substrates. In conclusion,the conventional wet-etching process of forming the circuit on the glasssubstrate having the ITO not is only time consuming and labor intensive,but also increases the overall thickness of the electronic device.Therefore, a process capable of integrating the element substrates isurgently needed.

In addition, due to pollution particles possibly existing on eachsubstrate, bubbles may be generated in substrate bonding and analignment problem of substrate bonding may also occur, which both affectthe yield of the fabrication process of the electronic device. Moreover,when the contact area is larger, the bonding complexity will be higher.Therefore, a process structure capable of reducing the number ofrequired substrates in the touch panel is urgently needed.

SUMMARY OF THE INVENTION

In order to effectively reduce the number of substrates in an electronicdevice, the present invention is directed to a touch panel, in which atouch circuit of the touch panel is integrated onto a cover lens, asubstrate of a color filter, or a polarizer, so as to reduce the numberof substrates that need to be bonded, thereby effectively avoidingproblems caused by substrate bonding and decreasing the overallthickness of the touch panel.

In a first embodiment, the present invention provides a touch panel,which includes a first substrate, a second substrate, and a thirdsubstrate. The first substrate includes a first side having a firstcircuit. The second substrate includes a first side arranged on thefirst side of the first substrate and a second side having a secondcircuit. The third substrate is arranged on the second side of thesecond substrate.

In a second embodiment, the present invention provides a touch panel,which includes a first substrate, a second substrate, and a thirdsubstrate. The first substrate includes a first side having a firstcircuit. The second substrate is arranged on the first side of the firstsubstrate. The third substrate includes another side arranged on asecond side of the second substrate, and the first side has a secondcircuit.

In a third embodiment, the present invention provides a touch panel,which includes a first substrate, a second substrate, and a thirdsubstrate. The second substrate includes a first side arranged on thefirst substrate, and the first side has a first circuit. The thirdsubstrate is arranged on a second side of the second substrate, and hasa second circuit at a side facing the second substrate.

In a fourth embodiment, the present invention provides a touch panel,which includes a first substrate, a second substrate, and a thirdsubstrate. The second substrate is arranged on the first substrate, anda first circuit and a second circuit are respectively provided on twosides of the second substrate. The third substrate is arranged on thesecond substrate.

In a fifth embodiment, the present invention provides a touch panel,which includes a first substrate and a second substrate. The firstsubstrate includes a first side having a circuit. The second substrateis arranged on the first side of the first substrate.

In a sixth embodiment, the present invention provides a touch panel,which includes a first substrate, a second substrate, and a thirdsubstrate. The second substrate is arranged on the first substrate, anda circuit is formed on a side of the second substrate. The thirdsubstrate is arranged on the second substrate.

In a seventh embodiment, the present invention provides a touch panel,which includes a first substrate, a second substrate, and a thirdsubstrate. The second substrate is arranged on the first substrate. Thethird substrate is arranged on the second substrate, and a circuit isformed on a side of the third substrate facing the second substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a structure of a conventional touch circuit;

FIG. 2 shows a conventional method for patterning an ITO substrate;

FIG. 3 shows a touch panel according to an embodiment of the presentinvention;

FIG. 4 shows a touch panel according to an embodiment of the presentinvention;

FIG. 5 shows a touch panel according to an embodiment of the presentinvention;

FIG. 6 shows a touch panel according to an embodiment of the presentinvention;

FIG. 7 shows a touch panel according to an embodiment of the presentinvention;

FIG. 8 shows a touch panel according to an embodiment of the presentinvention; and

FIG. 9 shows a touch panel according to an embodiment of the presentinvention.

DETAILED DESCRIPTION

FIG. 3 shows a structure of a touch panel according to the presentinvention, which includes a first substrate 301, a second substrate 302,and a third substrate 303. In such a structure, it can be consideredthat a circuit is formed on a first side of the first substrate 301facing the second substrate 302, two sides of the second substrate 302,and an inner side of the third substrate 303, that is, a side facing thesecond substrate.

In an embodiment of the present invention, on the first side of thefirst substrate 301, a conductive material is jet-printed through ajet-printing process, and unnecessary parts of the jet-printedconductive material are etched away by laser imprinting, so as to form afirst circuit 3011 on the first side of the first substrate 301. Thesecond substrate 302 is arranged on the first side of the firstsubstrate, and a second circuit 3021 is formed on a side opposite to thefirst substrate. The second circuit 3021 may be formed by the samemethod as the first circuit 3011. The third substrate 303 is arranged ona side of the second substrate 302 formed with the second circuit 3021.

In another embodiment, the first circuit 3011 and the second circuit3021 may be arranged on different layers, so as to achieve a multi-pointtouch function.

In addition, in another method for forming the first circuit, ITO ispre-formed on the first side of the first substrate 301, and unnecessaryparts of the ITO are etched away by laser imprinting, so as to form thefirst circuit 3011 on the first side of the first substrate 301. The twodry patterning methods are different from the conventional method forforming the circuit through wet-etching and suitable for integrationwith other substrates pre-formed with elements.

In an embodiment, the first substrate 301 is already provided with apre-formed color filter 3012 on a second side opposite the first side,and a planarization resin 3013 and an ITO rear electrode 3014 connectedto a lower liquid crystal 304 may even be already pre-formed on an outerside of the color filter 3012. Thus, for the integration of thesubstrate of the color filter 3012 and the substrate of the firstcircuit 3011, the first circuit 3011 must be formed through a drypatterning process. If a conventional wet-etching process is adopted toform a circuit on a rear side of the substrate of the color filter 3012,pre-formed elements such as color filter may be damaged. Thus, throughthe dry patterning process, the substrate of the color filter can beintegrated with the substrate on which a circuit is to be formed, so asto effectively reduce the number of required substrates, lower thecomplexity of substrate bonding, and decrease the overall thickness ofthe touch panel.

In a preferred embodiment, the first circuit 3011 is a driving circuitof the touch panel and the second circuit 3021 is a sensing circuit. Inanother embodiment, the second substrate 302 is a polarizer of the touchpanel, and the third substrate 303 is a cover lens on a surface of thetouch panel which has optical characteristics and serves to the touchelements.

In still another embodiment, the second substrate 302 may be an extraplastic substrate arranged between the polarizer and the cover lens 303,so that the second circuit 3021 can be formed on the plastic substrateby wet-etching or dry patterning.

In addition, a layer of UV film optical glue can be additionallyarranged between the second substrate and the third substrate, and thetwo substrates are bonded in a vacuum manner, so as to avoid problemssuch as unevenness, voids, alignment errors, or element damage caused inthe bonding process of the two substrates, thereby reducing thecomplexity of substrate bonding.

FIG. 4 shows a structure of another touch panel according to the presentinvention, which includes a first substrate 401, a second substrate 402,and a third substrate 403. A first circuit 4011 is formed by drypatterning on a first side of the first substrate 401. A secondsubstrate 402 is arranged on the first side of the first substrate 401.A third substrate 403 is further arranged on the second substrate 402. Asecond circuit 4031 is formed on a side of the third substrate facingthe second substrate. The second circuit 4031 is formed by drypatterning.

In a preferred embodiment, the first substrate 401 is already providedwith a pre-formed color filter 4012 on a second side opposite to thefirst side, and a planarization resin 4013 and an ITO rear electrode4014 may even be already pre-formed on an outer side of the color filter4012. Thus, through the dry patterning process, the substrate of thecolor filter can be integrated with the substrate of the first circuit4011, so as to effectively decrease the overall thickness of the touchpanel.

In a preferred embodiment, the first circuit 4012 is a driving circuitof the touch panel and the second circuit 4031 is a sensing circuit. Inanother embodiment, the second substrate 402 is a polarizer of the touchpanel and the third substrate 403 is a cover lens on a surface of thetouch panel.

In addition, a layer of UV film optical glue (UV glue) is additionallyarranged between the second substrate 402 and the third substrate 403,and the two substrates are bonded in a vacuum manner, so as to reducethe complexity of substrate bonding.

FIG. 5 shows a structure of another touch panel according to the presentinvention, which includes a first substrate 501, a second substrate 502,and a third substrate 503. A first circuit 5021 is formed by drypatterning on a first side of the second substrate 502 facing the firstsubstrate 501. A second circuit 5031 is formed on a side of the thirdsubstrate 503 facing the second substrate 502. The second circuit 5031may also be formed by dry patterning.

In a preferred embodiment, the second substrate 502 has a polarizer andthe third substrate 503 is a cover lens. Thus, the first circuit 5021and the second circuit 5031 are formed by dry patterning, so as not todamage the optical characteristics of the polarizer and the cover lens.In this case, the polarizer is integrated with the substrate of thefirst circuit and the cover lens is integrated with the substrate of thesecond circuit, so as to effectively decrease the overall thickness ofthe touch panel.

The first circuit 5021 may be a driving circuit of the touch panel andthe second circuit 5031 is a sensing circuit. In another embodiment, thesecond substrate 502 is an extra plastic substrate arranged between thepolarizer and the third substrate 503 (the cover lens).

Moreover, a layer of UV film optical glue is additionally arrangedbetween the second substrate 502 and the third substrate 503, and thetwo substrates are bonded in a vacuum manner.

FIG. 6 shows a structure of another touch panel according to the presentinvention, which includes a first substrate 601, a second substrate 602,and a third substrate 603. The second substrate 602 is arranged on thefirst substrate 601. A first circuit 6021 and a second circuit 6022 arerespectively formed on two sides of the second substrate 602. A thirdsubstrate 603 is arranged on a side of the second substrate 602 oppositeto the first substrate 601. In an embodiment, the first substrate 601 isalready provided with a pre-formed color filter 6012 on the sideopposite the side on which the second substrate 602 is to be arranged. Aplanarization resin 6013 and an ITO rear electrode 6014 may even bealready pre-formed on an outer side of the color filter 6012. Inaddition, the second substrate 602 may be a color filter. Thus, theformation of the first circuit 6021 and the second circuit 6022 on thetwo sides of the second substrate 602 through dry patterning will notdamage the original color filter. Besides, the circuit substrate withthe touch panel can be integrated with the substrate with the colorfilter, so as to effectively decrease the overall thickness of the touchpanel.

In another preferred embodiment, the second substrate 602 may be aplastic substrate, and circuits are formed on two sides of the plasticsubstrate through dry patterning, so as to enhance the yield of theprocess. In an embodiment, the first circuit 6021 is a driving circuitof the touch panel and the second circuit 6022 is a sensing circuit. Inaddition, the third substrate 603 arranged on the second substrate 602is a cover lens on a surface of the touch panel.

In an embodiment, the present invention further provides a touch panel,which includes a first substrate 701 and a second substrate 703 of thetouch panel. The second substrate 703 is arranged on a first side of thefirst substrate 701, and a circuit 7011 is formed on the first side ofthe first substrate 701. The circuit 7011 may be formed by drypatterning.

In a preferred embodiment, the second substrate 703 is a cover lenswhich has optical characteristics and protects the touch circuit.

In a preferred embodiment, the first substrate 701 is already providedwith a pre-formed color filter 7012 on a second side opposite the firstside, and a planarization resin 7013 and an ITO rear electrode 7014 mayeven be already pre-formed on an outer side of the color filter 7012.Thus, the substrate of the color filter can be integrated with thesubstrate of the circuit 7011 through dry patterning, so as toeffectively decrease the overall thickness of the touch panel.

In an embodiment, the ITO formed on the first side of the firstsubstrate 701 may be patterned into a strip structure through laserimprinting, so as to form touch patterns arranged in parallel. Ajet-printing process is further adopted to jet-print an insulatingmaterial and a conductive material on adjacent or parallel touchpatterns, so as to conduct the two touch patterns. Finally, thejet-printed insulating material and conductive material are furtherpatterned through laser imprinting, so as to form the circuit 7011. Inthis embodiment, the single layer touch circuit is single-point touch.In a preferred embodiment, the circuit 7011 includes a driving circuitand a sensing circuit of the touch panel.

In another embodiment, as shown in FIG. 7, a third substrate 702 isfurther provided between the first substrate 701 and the secondsubstrate 703, and is a polarizer of the touch panel.

FIG. 8 shows a structure of another touch panel according to the presentinvention, which includes a first substrate 801, a second substrate 802,and a third substrate 803 of the touch panel. The second substrate 802is arranged on a first side of the first substrate 801. The thirdsubstrate 803 is arranged on another side of the second substrate 802. Acircuit 8021 is formed on a side of the second substrate 802. Thecircuit is formed through dry patterning. In an embodiment, the firstsubstrate 801 is already provided with a pre-formed color filter 8012 onthe second side of the first substrate 801 opposite to the first side ofthe first substrate.

In a preferred embodiment, the second substrate 802 is a polarizer, theoptical characteristics of the polarizer will not be damaged through drypatterning, and the polarizer can be integrated with the circuit 8021,so as to further decrease the overall thickness of the touch paneleffectively. The third substrate 803 may be a cover lens on a surface ofthe touch panel.

In an embodiment, the circuit 8021 includes a driving circuit and asensing circuit of the touch panel. In addition, a layer of UV filmoptical glue is additionally arranged between the second substrate 802and the third substrate 803, and the two substrates are bonded in avacuum manner.

FIG. 9 shows a structure of another touch panel according to the presentinvention, which includes a first substrate 901, a second substrate 902,and a third substrate 903. The second substrate 902 is arranged on thefirst substrate 901, and the third substrate 903 is arranged on thesecond substrate 902. A circuit 9031 is formed on a side of the thirdsubstrate 903 facing the second substrate 902. The circuit is formed bydry patterning.

In a preferred embodiment, the third substrate 903 is a cover lens on asurface of the touch panel. The circuits are formed through drypatterning to avoid damage to the surface of the cover lens caused bythe etchant in the conventional wet-etching process, so that thesubstrate of the circuit 9031 can be integrated with the cover lens,thereby further decreasing the overall thickness of the touch paneleffectively.

In addition, the circuit 9031 includes a driving circuit and a sensingcircuit of the touch panel. Further, the first substrate 901 may includea color filter and the second substrate 902 may be a polarizer.Moreover, the second substrate 902 and the third substrate 903 may bebonded through UV film optical glue in a vacuum manner.

In the touch panel according to the present invention, the touch circuitof the touch panel can be integrated onto the cover lens, the substratewith the color filter, or the polarizer. Therefore, the number ofsubstrates that need to be bonded is reduced, so that the problemscaused during substrate bonding are effectively reduced and the overallthickness of the touch panel is also effectively decreased.

Although the technical solutions and features of the present inventionare illustrated as above, persons skilled in the art can still makevarious variations and modifications without departing from theteachings and disclosure of the present invention. Thus, the scope ofthe present invention is not limited to the disclosed embodiments butincludes other variations and modifications without departing from thepresent invention, and is as defined by the appended claims.

I claim:
 1. A touch panel, comprising; a first substrate comprising afirst surface and a second surface that are opposite to each other: asecond substrate being a polarizer that comprises, a first surfacearranged on the first surface side of the first substrate, and a secondsurface, the first surface of the polarizer and the second surface ofthe polarizer being opposite to each other; a circuit directly formed onthe first surface of the polarizer or the second surface of thepolarizer, the circuit comprising a driving circuit and a sensingcircuit; and a third substrate arranged on the second surface side ofthe polarizer; and further comprising a color filter directly formed onthe second surface of the first substrate, wherein the third substrateis a cover lens.